Asphaltic sheet materials including expandable graphite

ABSTRACT

A method for producing an asphaltic sheet, the method comprising of providing an asphaltic sheet; and applying expandable graphite particles to the asphaltic sheet.

This application is a continuation application of U.S. Ser. No.14/414,198 filed Jan. 12, 2015, which is a National-Stage Application ofPCT/US2013/050251 filed on Jul. 12, 2013 and a Continuation-in-Part ofU.S. Pat. No. 9,441,140 issued Sep. 13, 2016, and which claims thebenefit of U.S. Provisional Application Ser. No. 61/694,435 filed onAug. 29, 2012, U.S. Provisional Application Ser. No. 61/684,180 filed onAug. 17, 2012, and U.S. Provisional Application Ser. No. 61/670,864filed on Jul. 12, 2012, all of which are incorporated herein byreference.

FIELD OF THE INVENTION

Embodiments of the present invention are directed toward asphaltic sheetmaterials that include expandable graphite. These sheet materials areuseful as roofing underlayment, as roofing membranes, and as barriermaterials such as air, vapor, and/or moisture barriers.

BACKGROUND OF THE INVENTION

Asphaltic sheet materials are widely used in the construction industry.For example, polymer-modified asphaltic sheet material is used asmembrane for waterproofing flat or low-sloped roofs. As is known in theart, these roofing systems may include multiple layers of asphalticsheet including base sheets and cap sheets. Other examples includebarriers materials such air, vapor, or moisture barriers. Thesematerials are typically used on roofs or vertical surfaces such as wallsto provide the desired air, vapor and/or moisture resistance to astructure. Still other examples include underlayments, which are used inthe roofing industry to provide an extra layer of protection to theroof. This additional protection may provide, among other benefits,water, moisture, thermal, and/or fire resistance. As the name implies,underlayment is typically positioned below the external or primaryroofing protection, which may include shingles, membranes such aspolymeric or asphaltic membranes, roofing tiles, and metal panels orcladding.

With regard to underlayments, felt paper that is saturated with asphalthas historically been used as underlayment to provide additional waterand/or moisture resistance to the roof. Other forms of underlaymentinclude synthetic materials such as thermoplastic or thermoset materialsformed into sheets. Composites, such as laminates of asphalt andsynthetic polymer, have also been employed as underlayment.

In order to meet certain fire resistance properties, which may berequired by code or classification, fire or flame resistant underlaymentmay be employed. These underlayment may include textiles, includingwoven and non-woven fabrics, made of fire resistant materials such asfiberglass. These fabrics may include a coating, such as a mineralcoating, that further enhances the flame or fire resistance of theunderlayment.

Where there is a desire to achieve both moisture resistance and flame orfire resistance through the use of underlayment, such as with metalroofing systems, multiple underlayments are used. For example, a firstunderlayment may be used to provide moisture or water resistance, and asecond underlayment may be used to provide flame or fire resistance.This technique, however, suffers from several drawbacks including theadded difficulty of installing multiple underlayments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a cross section of an asphaltic sheetaccording to one or more embodiments of the present invention.

FIG. 2 is a cross-sectional view of an asphaltic sheet according to oneor more embodiments of the present invention.

FIG. 3 is a cross-sectional view of an asphaltic sheet according to oneor more embodiments of the present invention.

FIG. 4 is a perspective view of a building structure having a metal ortile roofing system including an asphaltic sheet according toembodiments of the present invention.

FIG. 5 is a perspective view of a building structure having a flatroofing system including an asphaltic sheet according to embodiments ofthe present invention.

FIG. 6 is a perspective view of a building structure having a wallsystem including an asphaltic sheet according to embodiments of thepresent invention.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide an asphalticsheet comprising an asphaltic component including an asphalt binder andexpandable graphite.

Still other embodiments of the present invention provide a roof systemcomprising a roof deck; an underlayment; and one or more metal panels orroofing tiles covering the underlayment, where the underlayment includesan asphaltic component including an asphalt binder and expandablegraphite dispersed within the asphalt binder.

Still other embodiments of the present invention provide a method forproducing an asphaltic sheet, the method comprising preparing a moltenasphaltic composition by introducing an expandable graphite to anasphalt binder at a temperature below that which will cause deleteriousexpansion of the expandable graphite, and fabricating an asphaltic sheetwith the molten asphaltic composition.

Still other embodiments of the present invention provide an asphalticsheet comprising an asphaltic component including an asphalt binder anda layer including expandable graphite, where said layer includingexpandable graphite is adjacent to said asphaltic component.

Still other embodiments of the present invention provide a method forproducing an asphaltic sheet, the method comprising providing anasphaltic sheet, and applying expandable graphite particles to theasphaltic sheet.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present invention are based, at least in part, on thediscovery of an asphaltic sheet having an asphaltic component withexpandable graphite. In certain embodiments, the asphaltic sheetincludes an asphalt component with the expandable graphite dispersedwithin the asphalt component. In these or other embodiments, theasphaltic sheet includes a layer of expandable graphite adjacent to theasphalt component. In one or more embodiments, the asphaltic sheet isadvantageously resistant to water, moisture, an/or air due to theasphaltic nature of the sheet, and it is also flame resistant due to thepresence of the expandable graphite. It is believed that one or moreadvantages of the present invention derive from the presence of theexpandable graphite within or adjacent to the asphaltic component of thesheet. While the prior art contemplates the use of expandable graphiteas a flame retardant, the prior art does not contemplate incorporatingthe expandable graphite into the asphaltic component of a sheet materialor placing a layer of the expandable graphite adjacent to the asphalticcomponent. Embodiments of the present invention provide a method forincorporating the expandable graphite into the asphaltic component ofthe sheet without deleteriously expanding the graphite (i.e. thegraphite is not expanded to a deleterious degree). And, in certainembodiments, the asphaltic component of the sheet material furtherincludes a complementary flame retardant material that is believed tosynergistically interact with the expandable graphite to provideunexpected flame resistance.

Sheet Construction

In one or more embodiments, the asphaltic sheet is or includes a planarbody of asphalt material, which may also be referred to as the asphaltcomponent of the sheet or asphalt layer 12. For example, as shown inFIG. 1, asphaltic sheet 11 includes asphalt component 12 having a firstplanar surface 13 and second planer surface 14. Sheet 11 may include anoptional textile fabric 15 embedded or impregnated within asphalticcomponent 12. In certain embodiments, the sheet is devoid of a scrim orfabric. Asphaltic component 12, as will be described in greater detailbelow, may include various constituents such as polymeric modifiers andfillers, as well as expandable graphite 16 and optional complementaryflame retardants (not shown) according to the present invention. In oneor more embodiments, sheet 11 may further include one or more polymericlayers 17 laminated to asphalt component 12 of sheet 11. For example,asphaltic sheet 11 may include an asphaltic component 12 laminated to apolypropylene sheet. In other embodiments, layer 17 may include a layerof release agents, such as silica, sand or talc. Additionally, a releasefilm 19 may be removably secured to at least one of the exposed planarsurfaces 13 or 14.

In one or more embodiments, optional textile fabric 15, which may alsobe referred to as fabric reinforcement 15, reinforcing member 15, orsimply reinforcement 15, may include woven and/or non-woven fabrics.Various fabric reinforcements are known in the art, and practice of thepresent invention is not necessarily limited by the selection of aparticular fabric. In one or more embodiments, reinforcement 15 may befabricated from fiberglass and/or synthetic yards or filaments.Exemplary synthetic yarns include those prepared from polyesters orpolyimides.

In one or more embodiments, the thickness of asphaltic sheet 11 may beat least 10, in other embodiments at least 20, and in other embodimentsat least 30 mils. In these or other embodiments, the thickness ofasphaltic sheet 11 may be at most 120, in other embodiments at most 100,in other embodiments at most 90, and in other embodiments at most 80mils. In one or more embodiments, the thickness of asphaltic sheet 11may be from about 10 to about 100, in other embodiments from about 20 toabout 90, and in other embodiments from about 30 to about 80 mils. Inother embodiments, especially where the asphaltic sheet is used in avertical application, the thickness of the asphaltic sheet may besubstantially thinner. For example, the thickness of the sheet may beless than 20, in other embodiments less than 15, and in otherembodiments less than 10 mils, with the thickness ranging from 2 to 20mils, in other embodiments from 3 to 15 mils, and in other embodimentsfrom 5 to 10 mils.

In one or more embodiments, the weight of the asphaltic sheet may be atleast 5, in other embodiments at least 10 and in other embodiments atleast 15 pounds per hundred square feet. In these or other embodiments,the weight of the asphaltic sheet may be at most 90, in otherembodiments at most 70, and in other embodiments at most 50 pounds perhundred square feet. In these or other embodiments, the weight of theasphaltic sheet may be from 5 to 100, in other embodiments from 10 to80, and in other embodiments from 15 to 50 pounds per hundred squarefeet. In other embodiments, especially where the asphaltic sheet is usedin a vertical application, the weight of the asphaltic sheet may besubstantially lighter. For example, the weight of the sheet may be lessthan 60, in other embodiments less than 50, and in other embodimentsless than 40 pounds per hundred square feet, with the weight rangingfrom 5 to 60, in other embodiments from 10 to 50, and in otherembodiments from 15 to 40 pounds per hundred square feet.

In other embodiments, as shown, for example, in FIG. 2, asphaltic sheet11 includes asphaltic component 12 having first planer surface 13 andsecond planar surface 14. Adjacent to asphaltic component 12 is a layer18 including expandable graphite 16. Layer 18 may be adjacent toasphaltic component 12 as a result of the manner in which asphalticsheet 11 is fabricated, as will be described in greater detail below.Asphaltic sheet 11 may carry optional polymeric layer 17, which may alsobe referred to as polymeric liner 17. In other embodiments, layer 17 mayinclude a layer of release agents, such as silica, sand or talc. In yetother embodiments, layer 17 may be a glass scrim, polyester mat, metalfoil (e.g., aluminum foil), fabric, elastomeric layer, and the like.

In one or more embodiments, layer 18 includes one or more layers ofparticles of expandable graphite 16. These particles may be held inplace by a matrix of asphalt material present within at least a portionof layer 18. In these or other embodiments, the expandable graphite 16is held in place by being adhered to the surface of the asphalt. In oneor more embodiments, asphaltic component 12 may also include expandablegraphite dispersed therein. In other words, asphaltic sheet may includeexpandable graphite dispersed throughout the asphaltic component andlayer 18 of expandable graphite adjacent to component 12.

In one or more embodiments, layer 18 may include a planar region withinsheet 11 that includes a higher concentration of expandable graphiterelative to any other region of sheet 11. Thus, layer 18 may include acontinuous layer of expandable graphite having a variable or relativelyconstant thickness across sheet 11. Or, in other embodiments, theexpandable graphite may be discontinuous throughout the region so longas the concentration of expandable graphite within the region is higherthan in other areas or regions of sheet 11. In one or more embodiments,the discontinuity of the expandable graphite within the layer 18 mayresult from the asphaltic material which may form a matrix in which theexpandable graphite is at least partially dispersed within this regionor layer. It should also be appreciated that the concentration of theexpandable graphite may not be constant within this layer. Indeed, aswill be appreciated from the description of how to fabricate the sheetsof this embodiment, a concentration gradient may exist whereby theconcentration of the expandable graphite moves from a region of maximumconcentration to a region of decreased concentration. As shown inexpanded view in FIG. 2, the concentration of expandable graphite 16furthest from planar surface 13 within layer 18 is the highest, whichcorresponds to a minimum in asphalt concentration. On the other hand,the concentration of expandable graphite 16 proximate to planar surface13 is a minimum relative to the concentration of expandable graphitewithin layer 18.

In yet other embodiments, which may be described with reference to FIG.3, an additional layer of asphalt 12′ is adjacent expandable graphitelayer 18 opposite asphaltic component or layer 12. Layer 12′ may also bereferred to as a skin layer 12′, and aspects of this embodiment may bedescribed as layer or region 18 being embedded between layers ofasphaltic binder or material. Consistent with the other embodimentsdescribed above, this layer 12′ may include expandable graphite 16 at aconcentration lower than layer 18. Nonetheless, in one or moreembodiments, layer 12′ may include expandable graphite dispersedtherein, although the concentration is lower than the concentration ofthe expandable graphite within region 18. In fact, in one or moreembodiments, a concentration gradient may exist between layers 12′ and18 in a similar fashion to the concentration gradient described above.

While a continuous layer or region (e.g. region 18) is believed to beadvantageous, it is also contemplated that the sheet can includemultiple discreet regions of the expandable graphite, such as may existin a pattern where the expandable graphite is applied on the top of theasphaltic sheet in rows or strips in the machine direction of the sheet.This may be advantageous where greater adhesion to a top sheet (e.g.sheet 17) is desired.

In one or more embodiments, the thickness of layer 18 may be at least 10μm, in other embodiments at least 20 μm, in other embodiments at least30 μm, in other embodiments at least 75 μm, and in other embodiments atleast 100 μm. In these or other embodiments, the thickness of layer 18may be at most 3 mm, in other embodiments at most 2 mm, and in otherembodiments at most 1 mm. In one or more embodiments, the thickness oflayer 18 may be from about 10 μm to about 3 mm, in other embodimentsfrom about 75 μm to about 2 mm, and in other embodiments from about 100μm to about 1 mm.

In one or more embodiments, the thickness of layer 12′ may be at least 2μm, in other embodiments at least 5 μm, and in other embodiments atleast 20 μm. In these or other embodiments, the thickness of layer 12′may be at most 1 mm, in other embodiments at most 0.5 mm, in otherembodiments at most 0.25 mm, in other embodiments at most 0.1 mm, and inother embodiments at most 0.050 mm. In one or more embodiments, thethickness of layer 12′ may be from about 1 μm to about 3 mm, in otherembodiments from about 2 μm to about 0.5 mm, and in other embodimentsfrom about 5 μm to about 0.050 mm.

Asphalt and Constituents

As noted above, the asphaltic sheet of one or more embodiments of thepresent invention includes an asphaltic component. The asphalticcomponent includes an asphalt binder and expandable graphite dispersedwithin the binder. The asphaltic component may also include, dispersedwithin the binder, polymeric modifiers, fillers, tackifiers,complementary flame retardants, and other constituents conventionallyused in asphaltic-based building materials.

Asphalt Binder

The term “asphalt binder” is used as understood by those skilled in theart and is consistent with the meaning provided by AASHTO M320. As usedwithin this specification, the terms “asphalt” and “asphalt binder” maybe used synonymously. The asphalt binder material may be derived fromany asphalt source, such as natural asphalt, rock asphalt, produced fromtar sands, or petroleum asphalt obtained in the process of refiningpetroleum. In other embodiments, asphalt binders may include a blend ofvarious asphalts not meeting any specific grade definition. Thisincludes air-blown asphalt, vacuum-distilled asphalt, steam-distilledasphalt, cutback asphalt or roofing asphalt. Alternatively, gilsonite,natural or synthetic, used alone or mixed with petroleum asphalt, may beselected. Synthetic asphalt mixtures suitable for use in the presentinvention are described, for example, in U.S. Pat. No. 4,437,896. In oneor more embodiments, asphalt includes petroleum derived asphalt andasphaltic residual. These compositions may include asphaltenes, resins,cyclics, and saturates. The percentage of these constituents in theoverall asphalt binder composition may vary based on the source of theasphalt.

Asphaltenes include black amorphous solids containing, in addition tocarbon and hydrogen, some nitrogen, sulfur, and oxygen. Trace elementssuch as nickel and vanadium may also be present. Asphaltenes aregenerally considered as highly polar aromatic materials of a numberaverage molecular weight of about 2000 to about 5000 g/mol, and mayconstitute about 5 to about 25% of the weight of asphalt.

Resins (polar aromatics) include dark-colored, solid and semi-solid,very adhesive fractions of relatively high molecular weight present inthe maltenes. They may include the dispersing agents of peptizers forthe asphaltenes, and the proportion of resins to asphaltenes governs, toa degree, the sol- or gel-type character of asphalts. Resins separatedfrom bitumens may have a number average molecular weight of about 0.8 toabout 2 kg/mol but there is a wide molecular distribution. Thiscomponent may constitute about 15 to about 25% of the weight ofasphalts.

Cyclics (naphthene aromatics) include the compounds of lowest molecularweight in bitumens and represent the major portion of the dispersionmedium for the peptized asphaltenes. They may constitute about 45 toabout 60% by weight of the total asphalt binder, and may be dark viscousliquids. They may include compounds with aromatic and naphthenicaromatic nuclei with side chain constituents and may have molecularweights of 0.5 to about 9 kg/mol.

Saturates include predominantly the straight- and branched-chainaliphatic hydrocarbons present in bitumens, together with alkylnaphthenes and some alkyl aromatics. The average molecular weight rangemay be approximately similar to that of the cyclics, and the componentsmay include the waxy and non-waxy saturates. This fraction may fromabout 5 to about 20% of the weight of asphalts.

In these or other embodiments, asphalt binders may include bitumens thatoccur in nature or may be obtained in petroleum processing. Asphalts maycontain very high molecular weight hydrocarbons called asphaltenes,which may be soluble in carbon disulfide, pyridine, aromatichydrocarbons, chlorinated hydrocarbons, and THF. Asphalts or bituminousmaterials may be solids, semi-solids or liquids.

In one or more embodiments, the asphalt binder includes AC-5, AC-10 andAC-15. These asphalts typically contain about 40 to about 52 parts byweight of aromatic hydrocarbons, about 20 to about 44 parts by weight ofa polar organic compound, about 10 to about 15 parts by weight ofasphaltene, about 6 to about 8 parts by weight of saturates, and about 4to about 5 parts by weight of sulfur. Nevertheless, practice of thepresent invention is not limited by selection of any particular asphalt.

In one or more embodiments, the molecular weight of the aromatichydrocarbons present in asphalt may range between about 300 and 2000,while the polar organic compounds, which generally include hydroxylated,carboxylated and heterocyclic compounds, may have a weight averagemolecular weight of about 500 to 50,000. Asphaltenes, which aregenerally known as heavy hydrocarbons, are typically of a high molecularweight and are heptane insoluble. Saturates generally include paraffinicand cycloaliphatic hydrocarbons having about 300 to 2000 molecularweight.

In one or more embodiments, bitumens may be used. Bitumens are naturallyoccurring solidified hydrocarbons, typically collected as a residue ofpetroleum distillation. Gilsonite is believed to be the purest naturallyformed bitumen, typically having a molecular weight of about 3,000 withabout 3 parts by weight complexed nitrogen.

Expandable Graphite

Expandable graphite may also be referred to as expandable flakegraphite, intumescent flake graphite, or expandable flake; and, for thepurposes herein, these terms may be used interchangeably.

In one or more embodiments, expandable graphite includes intercalatedgraphite in which an intercallant material is included between thegraphite layers of graphite crystal or particle. Examples ofintercallant materials include halogens, alkali metals, sulfates,nitrates, various organic acids, aluminum chlorides, ferric chlorides,other metal halides, arsenic sulfides, and thallium sulfides. In certainembodiments of the present invention, the expandable graphite includesnon-halogenated intercallant materials. In certain embodiments, theexpandable graphite includes sulfate intercallants, also referred to asgraphite bisulfate. As is known in the art, bisulfate intercalation isachieved by treating highly crystalline natural flake graphite with amixture of sulfuric acid and other oxidizing agents which act tocatalyze the sulfate intercalation.

Commercially available examples of expandable graphite include HPMSExpandable Graphite (HP Materials Solutions, Inc., Woodland Hills,Calif.) and Expandable Graphite Grades 1721 (Asbury Carbons, Asbury,N.J.). Other commercial grades contemplated as useful in the presentinvention include 1722, 3393, 3577, 3626, and 1722HT (Asbury Carbons,Asbury, N.J.).

In one or more embodiments, the expandable graphite may be characterizedas having a mean or average size in the range from about 30 μm to about1.5 mm, in other embodiments from about 50 μm to about 1.0 mm, and inother embodiments from about 180 to about 850 μm. In certainembodiments, the expandable graphite may be characterized as having amean or average size of at least 30 μm, in other embodiments at least 44μm, in other embodiments at least 180 μm, and in other embodiments atleast 300 μm. In one or more embodiments, expandable graphite may becharacterized as having a mean or average size of at most 1.5 mm, inother embodiments at most 1.0 mm, in other embodiments at most 850 μm,in other embodiments at most 600 μm, in yet other embodiments at most500 μm, and in still other embodiments at most 400 μm. Useful expandablegraphite includes Graphite Grade #1721 (Asbury Carbons), which has anominal size of greater than 300 μm.

In one or more embodiments, the expandable graphite may be characterizedas having a median size in the range from about 30 μm to about 1.5 mm,in other embodiments from about 50 μm to about 1.0 mm, and in otherembodiments from about 180 to about 850 μm. In certain embodiments, theexpandable graphite may be characterized as having a median size of atleast 30 μm, in other embodiments at least 44 μm, in other embodimentsat least 180 μm, and in other embodiments at least 300 μm. In one ormore embodiments, expandable graphite may be characterized as having amedian size of at most 1.5 mm, in other embodiments at most 1.0 mm, inother embodiments at most 850 μm, in other embodiments at most 600 μm,in yet other embodiments at most 500 μm, and in still other embodimentsat most 400 μm.

In one or more embodiments of the present invention, the expandablegraphite may be characterized as having a nominal particle size of 20×50(US sieve). US sieve 20 has an opening equivalent to 0.841 mm and USsieve 50 has an opening equivalent to 0.297 mm. Therefore, a nominalparticle size of 20×50 indicates the graphite particles are at least0.297 mm and at most 0.841 mm.

In one or more embodiments, the expandable graphite may be characterizedas having a carbon content in the range from about 80% to about 99%. Incertain embodiments, the expandable graphite may be characterized ashaving a carbon content of at least 80%, in other embodiments at least85%, in other embodiments at least 90%, in yet other embodiments atleast 95%, in other embodiments at least 98%, and in still otherembodiments at least 99% carbon.

In one or more embodiments, the expandable graphite may be characterizedas having a sulfur content in the range from about 0% to about 8%, inother embodiments from about 2.6% to about 5.0%, and in otherembodiments from about 3.0% to about 3.5%. In certain embodiments, theexpandable graphite may be characterized as having a sulfur content ofat least 0%, in other embodiments at least 2.6%, in other embodiments atleast 2.9%, in other embodiments at least 3.2%, and in other embodiments3.5%. In certain embodiments, the expandable graphite may becharacterized as having a sulfur content of at most 8%, in otherembodiments at most 5%, in other embodiments at most 3.5%.

In one or more embodiments, the expandable graphite may be characterizedas having an expansion ratio (cc/g) in the range from about 10:1 toabout 500:1, in other embodiments at least 20:1 to about 450:1, in otherembodiments at least 30:1 to about 400:1, in other embodiments fromabout 50:1 to about 350:1. In certain embodiments, the expandablegraphite may be characterized as having an expansion ratio (cc/g) of atleast 10:1, in other embodiments at least 20:1, in other embodiments atleast 30:1, in other embodiments at least 40:1, in other embodiments atleast 50:1, in other embodiments at least 60:1, in other embodiments atleast 90:1, in other embodiments at least 160:1, in other embodiments atleast 210:1, in other embodiments at least 220:1, in other embodimentsat least 230:1, in other embodiments at least 270:1, in otherembodiments at least 290:1, and in yet other embodiments at least 300:1.In certain embodiments, the expandable graphite may be characterized ashaving an expansion ratio (cc/g) of at most 350:1, and in yet otherembodiments at most 300:1.

In one or more embodiments, the expandable graphite, as it exists withthe asphaltic component of the asphaltic sheet of the present invention,is partially expanded. In one or more embodiments, the expandablegraphite is not expanded, however, to a deleterious degree, whichincludes that amount or more of expansion that will deleteriously theability to form the sheet product and the ability of the graphite toserve as flame retardant at desirable levels, which include those levelsthat allow proper formation of the sheet. In one or more embodiments,the expandable graphite is expanded to at most 60%, in other embodimentsat most 50%, in other embodiments at most 40%, in other embodiments atmost 30%, in other embodiments at most 20%, and in other embodiments atmost 10% beyond its original unexpanded size.

In one or more embodiments, the expandable graphite may be characterizedas having a pH in the range from about 1 to about 10; in otherembodiments from about 1 to about 6; and in yet other embodiments fromabout 5 to about 10. In certain embodiments, the expandable graphite maybe characterized as having a pH in the range from about 4 to about 7. Inone or more embodiments, the expandable graphite may be characterized ashaving a pH of at least 1, in other embodiments at least 4, and in otherembodiments at least 5. In certain embodiments, the expandable graphitemay be characterized as having a pH of at most 10, in other embodimentsat most 7, and in other embodiments at most 6.

In one or more embodiments, the expandable graphite may be characterizedby an onset temperature ranging from about 100° C. to about 250° C.; inother embodiments from about 160° C. to about 225° C.; and in otherembodiments from about 180° C. to about 200° C. In one or moreembodiments, the expandable graphite may be characterized by an onsettemperature of at least 100° C., in other embodiments at least 130° C.,in other embodiments at least 160° C., and in other embodiments at least180° C. In one or more embodiments, the expandable graphite may becharacterized by an onset temperature of at most 250° C., in otherembodiments at most 225° C., and in other embodiments at most 200° C.Onset temperature may also be interchangeably referred to as expansiontemperature and also alternatively referred to as the temperature atwhich expansion of the graphite starts.

Polymeric Modifiers

In one or more embodiments, the polymeric modifier, which may simply bereferred to as polymer, includes thermoplastic polymers, thermosettingelastomers, thermoplastic elastomers, and/or mixtures thereof. Each ofthese polymers have been used, either alone or in combination with eachother to modify asphalt binders, and practice of the present inventionis not necessarily limited by the selection of any particular polymericmodifier.

In one or more embodiments, the polymers may be characterized by a glasstransition temperature (Tg), as measured by DSC analysis, of less than150° C., in other embodiment less than 125° C., in other embodiment lessthan 100° C., in other embodiments less than 20° C., in otherembodiments less than 0° C., in other embodiments less than −20° C., inother embodiments less than −35° C., and in other embodiments from about−90° C. to about −20° C. In these or other embodiments, the polymers maybe characterized by a glass transition temperature (Tg), as measured byDSC analysis, of more than −20° C., in other embodiments more than 0°C., in other embodiments more than 20° C., in other embodiments morethan 50° C., and in other embodiments more than 100° C.

In one or more embodiments, the polymeric modifier may be characterizedby a melt index (ASTM D-1238; 2.16 kg load @ 190° C.) of less than 1,000dg/min, in other embodiments less than 500 dg/min, in other embodimentsless than 50 dg/min, in other embodiments less than 20 dg/min, in otherembodiments less than 10 dg/min, and in other embodiments less than 1dg/min. In these or other embodiments, the unsaturated polymers may havea melt index of between 3 and 15 dg/min, and other embodiments between 4and 12 dg/min.

In one or more embodiments, the polymeric modifier may be characterizedby a number average molecular weight (M_(n)) of from about 10 to about1,000 kg/mol, in other embodiments from about 40 to about 500 kg/mol,and in other embodiments from about 80 to about 200 kg/mol. In these orother embodiments, the polymeric modifier may also be characterized by aweight average molecular weight (M_(w)) of from about 10 to about 4,000kg/mol, in other embodiments from about 40 to about 2,000 kg/mol, and inother embodiments from about 80 to about 800 kg/mol. In one or moreembodiments, the polymeric modifier may be characterized by a molecularweight distribution of from about 1.1 to about 5, in other embodimentsfrom about 1.5 to about 4.5, and in other embodiments from about 1.8 toabout 4.0. Molecular weight can be determined by gel permeationchromatography (GPC) calibrated with polystyrene standards and adjustedfor the Mark-Houwink constants for the polymer in question.

The polymeric modifier may be linear, branched, or coupled polymers.Types of polymers may include both natural and synthetic polymers.Useful synthetic polymers may include polydienes or polydiene copolymerswith non-diene comonomer (e.g., styrene). The copolymers may includeblock and random copolymers. The coupled polymers may include linearlycoupled polymers (e.g., di-coupled polymers) or raidally coupledpolymers (e.g., tri-coupled or, tetra-coupled penta-coupled,hexa-coupled etc.). Exemplary polydienes include polybutadiene andpolyisoprene. Exemplary copolymers may include random styrene-butadienerubber, styrene-butadiene block copolymer, styrene-butadiene-styreneblock copolymer, random styrene-isoprene, styrene-isoprene blockcopolymer, styrene-isoprene-butadiene block copolymer, randomstyrene-isoprene-butadiene, styrene-isoprene-styrene block copolymer,and chloroprene rubber. In one or more embodiments, the polymericmodifier include linear or radial block copolymers wherein the blockcopolymers include terminal styrene blocks. In these or otherembodiments, the styrene content of these block copolymers may be from10% to 50% by weight, in other embodiments from 15% to 45% by weight,and in other embodiments from 20% to 40% by weight.

In one or more embodiments, the polymeric modifier is an SBS blockcopolymer (i.e., poly(styrene-b-butadiene-b-styrene). In one or moreembodiments, these block copolymers may be characterized by a weightaverage molecular weight of from about 90,000 to about 750,000, or inother embodiments from about 150,000 to about 250,000. In these or otherembodiments, these polymers may be characterized by a polydispersity ofup to about 1.1 or in other embodiments up to about 1.05. In particularembodiments, the SBS block copolymers have from about 27 to about 43parts by weight of styrene.

An example of an SBS block copolymer useful for practice of the presentinvention is that sold under the tradename Kraton D (Kraton PolymerGroup), including, for example, D1118, D1101, and D1184. Included amongthese polymers are SBS block linear and radial block copolymers. Inparticular embodiments, two block copolymers, linear and radial, can bemixed to achieve the desired results. In certain embodiments, the weightratio of linear to radial SBS copolymers may be from about 0 to about 7parts by weight of radial and from about 7 to about 15 parts by weightof linear SBS block copolymer.

In one or more embodiments, useful thermoplastic polymers that may usedas the polymeric modifier include polyolefins. For example, severalderivatives of polypropylene are useful including those prepared byfirst dimerizing propylene to give 4-methyl-1-pentene and subsequentlypolymerizing this dimer to give poly-4-methyl-1-pentene. Thesepolypropylenes may have a weight average molecular weight of from about50,000 to about 250,000, or in other embodiments from about 150,000 toabout 170,000. In one or more embodiments, the polydispersity may befrom about 2.5 to about 3.5. The polypropylene may be furthercharacterized by a melt temperature of from about 160° C. to about 175°C., and may have a cold crystallization temperature above 120° C.

In one or more embodiments, the polymeric modifier is isotacticpolypropylene (IPP). In one or more embodiments, the IPP has at least 45percent by weight crystallinity, or in other embodiments from about 46to about 50 percent by weight crystallinity. Blends of atacticpolypropylene and isotactic polypropylene may be used. In yet otherembodiments, atactic polyalpha olefins (APAOs) may be used.

Complementary Flame Retardants

As mentioned above, the expandable graphite may be used in conjunctionwith a complementary flame retardant. Flame retardants may include anycompound that increases the burn resistivity, particularly flame spreadsuch as tested by UL 94 and/or UL 790, in the polymeric compositions ofthe present invention. Generally, useful flame retardants include thosethat operate by forming a char-layer across the surface of a specimenwhen exposed to a flame. Other flame retardants include those thatoperate by releasing water upon thermal decomposition of the flameretardant compound. Useful flame retardants may also be categorized ashalogenated flame retardants or non-halogenated flame retardants.

Exemplary non-halogenated flame retardants include magnesium hydroxide,aluminum trihydrate, zinc borate, ammonium polyphosphate, melaminepolyphosphate, and antimony oxide (Sb₂O₃). Magnesium hydroxide (Mg(OH)₂)is commercially available under the tradename Vertex™ 60, ammoniumpolyphosphate is commercially available under the tradename Exolite™ AP760 (Clarian), which is sold together as a polyol masterbatch, melaminepolyphosphate is available under the tradename Budit™ 3141 (Budenheim),and antimony oxide (Sb₂O₃) is commercially available under the tradenameFireshield™.

Examples of other complementary calcium borate, magnesium hydroxide,basic magnesium carbonate, aluminum trihydrate, zinc borate, gypsum, andmixtures thereof. In these or other embodiments, the complementary flameretardant includes colemanite, which is a borate mineral that isbelieved to include about 50-80% calcium borate.

Tackifier Resin

In one or more embodiments, the asphaltic component may includetackifier resins. These resins include, but are not limited to,petroleum resins, synthetic polyterpenes, resin esters and naturalterpenes, and combinations thereof. In certain embodiments, the resinmodifiers soften or become liquid at temperatures of about 40° C. toabout 150° C. In certain embodiments, the resin modifiers have numberaverage molecular weights, as measured by vapor phase osmometry, belowthat of the polymeric material included in the polymeric film. Incertain embodiments, the number average molecular weights of the resinmodifiers are less than about 5,000. In other embodiments, the numberaverage molecular weights of the resin modifiers are less than about1,000. In additional embodiments, the number average molecular weightsof the resin modifiers are from about 500 to about 1000.

In certain embodiments, the resin modifiers have ring and ball softeningpoint of about 20° C. to about 160° C. In additional embodiments, resinmodifiers have ring and ball softening points of about 40° C. to about160° C. In still other embodiments, resin modifiers have ring and ballsoftening points of about 50° C. to about 160° C.

Various types of natural and synthetic resins, alone or in admixturewith each other, may be used be selected as the resin modifier. Suitableresins include, but are not limited to, natural rosins and rosin esters,hydrogenated rosins and hydrogenated rosin esters, coumarone-indeneresins, petroleum resins, polyterpene resins, and terpene-phenolicresins. Specific examples of suitable petroleum resins include, but arenot limited to, aliphatic hydrocarbon resins, hydrogenated aliphatichydrocarbon resins, mixed aliphatic and aromatic hydrocarbon resins,hydrogenated mixed aliphatic and aromatic hydrocarbon resins,cycloaliphatic hydrocarbon resins, hydrogenated cycloaliphatic resins,mixed cycloaliphatic and aromatic hydrocarbon resins, hydrogenated mixedcycloaliphatic and aromatic hydrocarbon resins, aromatic hydrocarbonresins, substituted aromatic hydrocarbons, and hydrogenated aromatichydrocarbon resins. As used herein, “hydrogenated” includes fully,substantially and at least partially hydrogenated resins. Suitablearomatic resins include aromatic modified aliphatic resins, aromaticmodified cycloaliphatic resin, and hydrogenated aromatic hydrocarbonresins. Any of the above resins may be grafted with an unsaturated esteror anhydride to provide enhanced properties to the resin. For additionaldescription of resin modifiers, reference can be made to technicalliterature, e.g., Hydrocarbon Resins, Kirk-Othmer, Encyclopedia ofChemical Technology, 4th Ed. v.13, pp. 717-743 (J. Wiley & Sons, 1995).

In one or more embodiments, the tackifier resins include phenol-basedresins. Included among the phenol-based resins are phenolic resins.These resins may include reactive phenol resins (also referred to asfunctionalized phenol resins), as well as unreactive resins. In one ormore embodiments, the phenolic resin is a resole resin, which can bemade by the condensation of alkyl, substituted phenols, or unsubstitutedphenols with aldehydes such as formaldehyde in an alkaline medium or bycondensation of bi-functional phenoldialcohols. In one or moreembodiments, this condensation reaction occurs in the excess or molarequivalent of formaldehyde. In other embodiments, the phenolic resin maybe formed by an acid-catalyzed reaction.

In one or more embodiments, the tackifier resin is a polybutene polymeror oligomer. In particular embodiments, polybutene oils are employed.Useful polybutene oils include high-viscosity oils that may becharacterized by a viscosity at 100° C. of at least 80 cst, in otherembodiments at least 100 cst, or in other embodiments at least 120 cstup to, for example, about 700 or 800 cst. In these or other embodiments,the high viscosity polybutene oils may be characterized by a molecularweight of at least 1000 g/mole, in other embodiments at least 1200g/mole, or in other embodiments at least 1300 g/mole up to, for example,1400 or 1500 g/mole. An exemplary high-viscosity polybutene oil isavailable under the tradename Indapol H300 (Ineos) or PB32 (Soltex).

Other Constituents

In one or more embodiments, the asphaltic component may include oil,which may also be referred to as processing oil or extender oil. Theseextenders may include high-boiling hydrocarbons. Examples of these oilsinclude paraffinic oils, aromatic oils, naphthenic oils, vegetable oils,and low PCA oils including MES, TDAE, and SRAE, and heavy naphthenicoils, and various synthetic oils such as, but not limited, polybuteneoils. In one or more embodiments, the oil employed is selected basedupon its compatibility with the rubber, as well as its ability toprovide advantageous properties to the final composition (e.g., greenstrength or tack). In these or other embodiments, the asphalticcomponent may also include fillers, extenders, antioxidants, waxes,antiozonants, and the like. Useful fillers include, but are not limitedto, inorganic fillers such as calcium carbonate (i.e., limestone) andglass, such as glass beads.

Amounts

In one or more embodiments, the asphaltic component of the asphalticsheet of the present invention includes at least 0.5, in otherembodiments at least 1, in other embodiments at least 3 and in otherembodiments at least 5 parts by weight expandable graphite per 100 partsby weight asphalt binder. In these or other embodiments, the asphalticcomponent of the asphaltic sheet of the present invention includes atmost 40, in other embodiments at most 30, and in other embodiments atmost 20 parts by weight expandable graphite per 100 parts by weightasphalt binder. In one or more embodiments, the asphaltic component ofthe asphaltic sheet of the present invention includes from about 0.5 toabout 40, in other embodiments from about 1 to about 30, and in otherembodiments from about 3 to about 20 parts by weight expandable graphiteper 100 parts by weight asphalt binder.

In one or more embodiments, the asphaltic component of the asphalticsheet of the present invention includes at least 0.5, in otherembodiments at least 1, in other embodiments at least 3, and in otherembodiments at least 5 parts by weight polymeric modifier per 100 partsby weight asphalt binder. In these or other embodiments, the asphalticcomponent of the asphaltic sheet of the present invention includes atmost 40, in other embodiments at most 30, and in other embodiments atmost 20 parts by weight polymeric modifier per 100 parts by weightasphalt binder. In one or more embodiments, the asphaltic component ofthe asphaltic sheet of the present invention includes from about 0.5 toabout 40, in other embodiments from about 1 to about 30, and in otherembodiments from about 3 to about 20 parts by weight polymeric modifierper 100 parts by weight asphalt binder.

In one or more embodiments, the asphaltic component of the asphalticsheet of the present invention includes at least 0.5, in otherembodiments at least 1, in other embodiments at least 3, and in otherembodiments at least 5 parts by weight complementary flame retardant per100 parts by weight asphalt binder. In these or other embodiments, theasphaltic component of the asphaltic sheet of the present inventionincludes at most 40, in other embodiments at most 30, and in otherembodiments at most 20 parts by weight complementary flame retardant per100 parts by weight asphalt binder. In one or more embodiments, theasphaltic component of the asphaltic sheet of the present inventionincludes from about 0.5 to about 40, in other embodiments from about 1to about 30, and in other embodiments from about 3 to about 20 parts byweight complementary flame retardant per 100 parts by weight asphaltbinder.

In one or more embodiments, the asphaltic component of the asphalticsheet of the present invention includes at least 0.5, in otherembodiments at least 1, in other embodiments at least 3, and in otherembodiments at least 5 parts by weight tackifier resin per 100 parts byweight asphalt binder. In these or other embodiments, the asphalticcomponent of the asphaltic sheet of the present invention includes atmost 40, in other embodiments at most 30, and in other embodiments atmost 20 parts by weight tackifier resin per 100 parts by weight asphaltbinder. In one or more embodiments, the asphaltic component of theasphaltic sheet of the present invention includes from about 0.5 toabout 40, in other embodiments from about 1 to about 30, and in otherembodiments from about 3 to about 20 parts by weight tackifier resin per100 parts by weight asphalt binder.

In one or more embodiments, the asphaltic component of the asphalticsheet of the present invention includes at least 0, in other embodimentsat least 5, in other embodiments at least 10, and in other embodimentsat least 20 parts by weight filler other than flame retardant materialper 100 parts by weight asphalt binder. In these or other embodiments,the asphaltic component of the asphaltic sheet of the present inventionincludes at most 350, in other embodiments at most 100, in otherembodiments at least 70, in other embodiments at least 50, and in otherembodiments at most 40 parts by weight filler other than flame retardantmaterial per 100 parts by weight asphalt binder. In still otherembodiments, the asphaltic component of the asphaltic sheet of thepresent invention includes from 0 to 350, in other embodiments from 1 to100, and in other embodiments from 5 to 45 parts by weight filler otherthan flame retardant material per 100 parts by weight asphalt binder.

In one or more embodiments, the expandable graphite, complementary flameretardant, and filler may be referred to as dispersed solids within amatrix of the asphalt material (which for purposes of this definitionincludes the asphalt material plus other non-solid constituents such asthe polymer modifier and/or tackifier). The asphaltic binder, therefore,is the continuous phase in which the solids are dispersed. In one ormore embodiments, the asphaltic binder is a major volume fraction of theparticle/matrix system. In these or other embodiments, the asphalticbinder is a major weight fraction of the particle/matrix system. In oneor more embodiments, the weight ratio of asphaltic binder to solidsdispersed in the binder is at least 0.4:1, in other embodiments at least0.6:1, in other embodiments at least 0.7:1 in other embodiments at least0.8:1, in other embodiments at least 1:1, in other embodiments at least1.2:1, in other embodiments at least 1.5:1, in other embodiments atleast 2:1, in other embodiments at least 2.5:1, and in other embodimentsat least 3:1.

Method of Making Sheet

In one or more embodiments, the asphaltic sheet of the present inventionmay generally be prepared by using conventional techniques for formingasphaltic sheet. For example, the technique may include, in certainembodiments, saturating a reinforcing textile with a molten asphaltcomposition. The step of saturating the sheet may include submerging thereinforcing sheet into a bath of molten asphalt. In other embodiments,the step of saturating the sheet may include spraying, roll coating, orotherwise applying a molten asphalt composition to a reinforcing sheet.Where a reinforcing sheet is not employed, a molten asphalt material canbe applied to release paper or film and then processed into a sheet thatis devoid of reinforcing scrim.

In certain embodiments, the molten asphalt composition is prepared byintroducing the expandable graphite to a molten asphalt composition. Inone or more embodiments, the temperature of the molten asphaltcomposition at the time of introduction of the expandable graphite isless than 270° C., in other embodiments is less than 230° C., in otherembodiments less than 220° C., in other embodiments less than 210° C.,in other embodiments less than 200° C., in other embodiments less than190° C., in other embodiments less than 185° C., in other embodimentsless than 175° C., in other embodiments less than 165° C., in otherembodiments less than 155° C., and in other embodiments less than 145°C. In these or other embodiments, the temperature of the molten asphaltcomposition at the time of introduction of the expandable graphite is atleast 125° C., in other embodiments at least 140° C., in otherembodiments at least 150° C., in other embodiments at least 160° C., andin other embodiments at least 170° C. In one or more embodiments, thesetemperatures are maintained during mixing and processing in the presenceof the expandable graphite.

In one or more embodiments, the molten asphalt composition is preparedin a multi-stage process whereby the asphalt binder and optionally oneor more additional ingredients (e.g. polymer modifier), other than theexpandable graphite, are mixed at elevated temperatures up to, forexample, 250° C., in other embodiments up to 240° C., in otherembodiments up to 230° C., in other embodiments up to 220° C., and inother embodiments up to 210° C. Following this initial mix, theasphaltic composition is cooled below 200° C., in other embodimentsbelow 190° C., and in other embodiments below than 185° C., in otherembodiments below 175° C., in other embodiments below 165° C., in otherembodiments below 155° C., and in other embodiments below 145° C.

In one more embodiments, cooling of the asphalt may take place my addingadditional asphalt to the mixture, where the temperature of the addedasphalt is cooler then the asphalt heated and mixed in the first step.For example, asphalts are typically flowable at temperatures as low asabout 130° C. to about 150° C. Accordingly, asphalt having a temperatureof about 130° C. to about 150° C. can be added to the asphalt mixtureprepared in the first mixing step to quickly and homogeneously cool theasphalt.

Following the cooling step, the expandable graphite is introduced to themolten asphalt composition and mixed at temperatures of less than 200°C., in other embodiments less than 190° C., in other embodiments lessthan 185° C., in other embodiments less than 175° C., in otherembodiments less than 165° C., in other embodiments less than 155° C.,and in other embodiments less than 145° C.

In an exemplary process, a reinforcing sheet, which may be in the formof a planar sheet and may be provided in the form of a roll, isprovided. In one or more embodiments, reinforcing sheet may be a scrim,or fiberglass mesh sheet, as is known in the art. Useful scrims includethose that are commercially available. For example, fiberglass scrimsare available under the trade name STYLE™ 930120 (Milliken & Co.;Spartanburg, S.C.) and also available from J. P. Stevens (Greenville,S.C.). In other embodiments, reinforcing sheet may be an organic felt ora combination polyester and glass mat. Useful polyester mats areavailable from Freudenberg & Co. of Germany. In one or more embodiments,the asphalt coater may be a reservoir of hot liquid asphalt. In otherembodiments, the asphalt coater may include spraying apparatus to coatthe reinforcing sheet with liquid asphalt. In yet other embodiments,reinforcing sheet may be coated with hot liquid asphalt by anyalternative methods known to persons having ordinary skill in the art.

In one or more embodiments, the reinforcing sheet is drawn through anasphalt coater, which applies hot liquid (i.e., molten asphalt) to thereinforcing sheet to create a sheet that is saturated with asphalt. Asnoted above, the asphalt composition includes may include polymericmodifiers, fillers, and other ingredients conventionally employed withasphalt compositions.

In one or more embodiments, the asphalt composition may include theexpandable graphite according to the practice of this invention. Inother words, the expandable graphite is added to the molten asphaltcomposition prior to the introduction of the reinforcing sheet to themolten asphalt. Also included within the molten asphalt may becomplementary flame retardant and other ingredients mentioned above.

In other embodiments, the molten asphalt composition is devoid orsubstantially devoid of expandable graphite. In these embodiments, theexpandable graphite is incorporated into the asphaltic sheet downstreamof the bath or reservoir of molten asphalt. For example, the expandablegraphite can be dropped onto the sheet after leaving the coater.

In yet other embodiments, the expandable graphite is included in themolten asphalt composition prior to the introduction of the reinforcingsheet to the molten asphalt and the expandable graphite is incorporatedinto the asphaltic sheet downstream of the bath or reservoir of moltenasphalt (e.g., by dropping).

In one or more embodiments, expandable graphite particles are dropped onto a sheet that has been coated with molten asphalt, wherein the asphaltmay or may not include expandable graphite. These particles are droppedat a rate and amount to create at least a partial layer of expandablegraphite particles adjacent to the asphalt of the coated asphalt sheet.In one or more embodiments, the act of dropping the expandable graphiteparticles on to a coated sheet may at least partially embed some of thegraphite particles in to the asphalt such that the asphalt serves as abinder to hold the graphite particles in place. In these or otherembodiments, one or more of the plurality of expandable graphiteparticles are adhered to the surface of the coated asphalt sheet by wayof the adhesive properties of the asphalt material. In one or moreembodiments, the step of dropping the expandable graphite creates aconcentration gradient of the expandable graphite and the asphalt.

In one or more embodiments, the process of dropping expandable graphiteparticles on to an asphaltic sheet takes place after the asphaltic sheetis prepared from a molten asphalt composition and prior to a substantialcooling of the asphalt material so as to take advantage of the adhesiveproperties of the asphalt. In one or more embodiments, at least aportion of the expandable graphite particles are dropped on or otherwiseapplied to the coated asphalt sheet within 15 seconds, in otherembodiments within 10 seconds, and in other embodiments within 5 secondsof the asphaltic sheet being prepared (e.g., removal of the asphalticsheet from a molten bath in which the asphaltic sheet is prepared). Inone or more embodiments, the expandable graphite is dropped on theasphaltic sheet prior to solidification of the asphalt material (e.g.,prior to the asphaltic sheet cooling to a temperature below about 85° C.

In one or more embodiments, the expandable graphite particles areapplied to the surface of an asphaltic sheet using a multi-stageprocess. For example, a multi-stage process may include multiple dropsof graphite particles. In certain embodiments, the various stages ordrops can be configured to achieve certain characteristics. For example,different sized expandable graphite particles can be dropped atdifferent stages in order to achieve desirable coverage of the surfaceof the asphaltic sheet.

In one or more embodiments, additional asphaltic material applied to thesheet after application of the expandable graphite (e.g., after droppingthe expandable graphite onto the sheet, which can form the layer ofexpandable graphite or concentrated region of expandable graphite). Thismay take place by using curtain coating or roll coating techniques. Inother embodiments, the expandable graphite is dropped onto the hotasphaltic sheet prior to the sheet being calendered or sized within anip roll. As a result, then the sheet is calendered or sized within anip roll, the excess asphaltic material at the nip roll will serve toform a layer (or skin) of asphaltic material over the layer ofexpandable graphite.

In certain embodiments, a polymeric layer is applied to the asphalticsheet after application of the expandable graphite particles. Forexample, following one or more drops or applications of the expandablegraphite particles to a surface of the asphaltic sheet, a polymeric filmmay be applied over the expandable graphite particles. In one or moreembodiments, this may facilitate subsequent calendaring of the asphalticsheet carrying the expandable graphite particles. In other embodiments,the layer of expandable graphite particles may be modified by theapplication of a release agent, such as sand, silica, or talc, over theexpandable graphite particles. The presence of release agents may, likethe polymeric film, facilitate subsequent calendaring of the asphalticsheet.

In one or more embodiments, the asphaltic sheet may be drawn through acooling station to cool the hot asphalt and create a more stablesubstrate for the application of granules. In one or more embodiments,the cooling station may include a water reservoir through which theasphaltic sheet is drawn. In certain embodiments, the asphaltic sheetmay float across a water reservoir to cool the sheet while allowing thetop surface to retain a higher temperature than the bottom surface. Inother embodiments, the cooling station may include other coolingmechanisms known to those skilled in the art.

INDUSTRIAL APPLICABILITY

In one or more embodiments, the asphaltic sheet of the present inventionmay be used as an underlayment. For example, the sheet may be employedas an underlayment within a metal roofing system. In one or moreembodiments, the metal roofing system may include a roof deck, anoptional insulation layer, the underlayment of the present invention,and metal panels, which may also be referred to as metal cladding. Inother embodiments, the asphaltic sheet of the present invention may beemployed as an underlayment within a tile roofing system. In one or moreembodiments, the tile roofing system may include a roof deck, anoptional insulation layer, the underlayment of the present invention,and roofing tiles.

Practice of the present invention is not necessarily limited by the typeof roof deck. For example, the roof deck may include a flat roof, alow-slope roof, or a high-slope roof. The deck may be fabricated fromwood, metal, concrete, or any material useful for fabricating a roofdeck.

As is known in the art, the insulation layer may include insulationboards such as polyisocyanurate or polystyrene insulation boards. Theseinsulation boards may be secured to the roof deck using knowntechniques, such as adhesive bonding or mechanical fastening.

In one or more embodiments, the underlayment may be applied directly tothe roof deck and the insulation boards can be applied over theunderlayment. In other embodiments, the underlayment may be applied overthe optional insulation layer. Where an insulation layer is not present,the underlayment may be applied directly to the deck.

In one or more embodiments, the metal panels or tile are then secured tothe roof on top of the underlayment. Where the insulation board isapplied over the underlayment, the metal panels or tiles may be securedover the insulation layer using known techniques.

For example, FIG. 4 shows a building structure 40 having a roof system41 including a roof deck 42, an asphaltic sheet 46 according to one ormore embodiments of the present invention, and a weather-resistantcovering 48, which may include metal cladding or tile. An optionalinsulation layer may be positioned above or below asphaltic sheet 46. Inone or more of the embodiments, asphaltic sheet 46 may operate as anunderlayment in roofing system 41.

In other embodiments, the asphaltic sheet of the present invention maybe used as a barrier sheet, which may also be referred to as a material.These barrier materials may include air barriers, which are employed toprevent or reduce the flow of oxygen and nitrogen into and/or out of abuilding structure. In other embodiments, these barrier materials mayinclude vapor barriers, which are employed to prevent or reduce the flowof water vapor into and/or out of a building structure. In yet otherembodiments, these barrier materials include moisture barriers, whichare employed to prevent or reduce the flow of moisture (i.e., liquidwater) into and/or out of a building structure.

For example, FIG. 5 shows a building structure 50 having a flat roofsystem 51 including roof deck 52, asphaltic sheets 58 according toembodiments of the present invention, insulation layer 54, andweather-resistant layer 56. Asphaltic sheet 58, which may operate as avapor barrier, may be above or below insulation layer 54.

In one or more embodiments, the barrier sheet may be applied to avertical surface (such as a wall) of a building structure. Usingconventional techniques, the barrier may be applied to the exteriorsurface of a building structure prior to application of the externalsheathing, such as metal wall panels, brick, composite siding, woodsiding, or vinyl siding.

For example, FIG. 6 shows a building structure 60 having a wall system62 including structural supports 63, insulation layer 64, asphalticsheet 66 according to embodiments of the present invention, and exteriorcladding 68. Asphaltic sheet 66, which may operate as a vapor barrier inthe wall system, may be positioned on the interior or exterior ofinsulation layer 64.

In still other embodiments, the asphaltic sheet may be used as a roofingmembrane. For example, the asphaltic sheet may be used as a base sheetor cap sheet in an asphaltic roofing membrane system. In one or moreembodiments, these asphaltic membranes are modified asphaltic membranesof the type known in the art. Examples of these membranes, albeitwithout the expandable graphite, are shown in U.S. Pat. Nos. 6,492,439,6,486,236, 4,835,199, 7,442,270, 7,146,771, 7,070,843, 4,992,315, and6,924,015, which are incorporated herein by reference.

Characteristics of Asphaltic Sheet

In one or more embodiments, the present invention provides a metalroofing system or tile roofing system wherein the asphaltic sheet of oneor more embodiments of the present invention is employed as anunderlayment, and the roofing system is characterized as a Class Aroofing system pursuant to UL and/or ASTM classifications; this is infact true where a single layer of the asphaltic sheet employed withinthe roofing system as the sole fire barrier. In one or more embodimentsof the present invention, the asphaltic sheets of the present inventioncan be used in a roofing system that can meet the performance standardsof the Burning Brand test of UL 790. In fact, the roofing system caninclude a single sheet of the asphaltic sheets of the present inventionas the sole fire barrier and can meet the performance standards of theBurning Brand test of UL 790. In other embodiments, the asphaltic sheetmay be used in a wall system to meet the performance standards ofNFPA-285.

In one or more embodiments, the asphaltic sheet of the present inventionis advantageously moisture resistant and can meet the requirements ofASTM D1970-09. In these or other embodiments, the asphaltic sheets arecharacterized by a water vapor transmission, as defined by ASTM E96, ofless than 1.0, in other embodiments less than 0.5, in other embodimentsless than 0.1, and in other embodiments less than 0.08 g/hr-m².

In one or more embodiments, the asphaltic sheets of the presentinvention are advantageously self-adhering (e.g., can be self-adhered toa substrate), which properties derive, at least in part, from theasphaltic nature of the matrix in which the other constituents aredispersed. In certain embodiments, this advantage is also believed toderive, at least in part, from the amount of asphalt material present inthe sheet relative to the other constituents of the sheet (e.g., thesolid such as filler and flame retardants). Additionally, the asphalticsheet of certain embodiments is advantageously self-sealing; in otherwords, the sheet can form a water-tight seal around nail holes and thelike. Again, the advantage is believed to derive from the level ofasphaltic material present in the sheet of certain embodiments.

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXPERIMENTAL Samples 1-4

Laboratory-scale asphaltic membranes were prepared by employing theingredients set forth in Table I, which shows the ingredients in percentby weight. The membranes were then subjected to burn tests, and theresults of those tests are likewise provided in Table I.

The membranes were formed by first preparing an asphaltic mixture andthen fabricating a membrane from the mixture. The fabrication techniqueincluded embedding a glass scrim into the membrane. Specifically, theasphaltic composition was prepared by heating the asphalt to about 300°F. and then adding the SBS copolymers to the molten asphalt under mediumto high shear through the use of a conventional mixing apparatus. Mixingcontinued for close to 20 minutes until the mixture appeared to besmooth and uniform, which was indicative of the fact that the polymersdissolved. The temperature of the mixture during the process peaked ataround 340-380° F. Following the addition of the SBS copolymers, theother fillers (excluding expandable graphite) and tackifiers were addedunder similar shear while generally maintaining the same temperature.The mixture was then allowed to cool to 300-350° F., and then theexpandable graphite was added while mixing continued for about 2minutes. Once it was determined that the graphite was evenlydistributed, the membrane was fabricated. The membrane was generallyfabricated by pouring the mixture on to a release paper on which theglass scrim was positioned. Spacers were placed at the edges of therelease paper to control the membrane thickness, and a release paper wasthen applied over the top of the mixture and pressed to form a flatmembrane. Once the membrane was cooled for sufficient handling, the testsample was prepared by stapling the membrane to a 4″×5″ plywood or OSBboard. A thermocouple was sandwiched between the membrane sample and thewood. The test samples were then suspended at a 5/12 slope. A propanetorch having a 4″ long flame was positioned so that the tip of the flamewas close to the sample without touching the sample.

TABLE I Samples 1 2 3 4 Ingredients Asphalt 83.80 81.80 76.10 83.80Expandable Graphite 3.00 5.00 7.10 0 SBS Copolymer I 3.40 3.40 4.20 3.4SBS Copolymer II 3.50 3.50 4.30 3.5 Tackifler 6.30 6.30 8.30 6.3 BurnTest Data Highest Temp. (° F.) 577.00 576.00 467.00 — Time @ highest4:00 5:00 5:00 — Temp. (Min.) Flow Slow flow, Very slow flow, No flow, —thick char thick char thick char Self-extinguishing 105 5 45 — (Fire out@ Sec) Exposure of Glass No No No — Scrim

The asphalt was obtained under the tradename AC-5 (Marathon); SBS I wasobtained under the tradename D1184 (Kraton); SBS II was obtained underthe tradename D1118 (Kraton); the tackifier resin was obtained under thetradename H300 (Ineos); and the expandable graphite was obtained underthe tradename 1721 (Asberry).

As suggested in Table I, Sample 4 was prepared without expandablegraphite. When subjected to the burn test, this sample began to burnrapidly and the asphaltic material began to flow rapidly. As a result,the test had to be terminated within the first minute for safetyreasons. In other words, the sample without expandable graphiteunequivocally failed. In contradistinction, Samples 1-3 show that thepresence of as little as 3 weight percent graphite withstood the burntest by forming a thick char, which resulted in little flow of theasphaltic material and ultimately the fire was self-extinguished withinless than 2 minutes of removal of the flame.

Samples 5-32

Using procedures similar to those described for samples 1-4, 28additional samples were prepared wherein colmanite was also added to theasphaltic mixture, together with expandable graphite. The specificrecipes for each asphaltic membrane is set forth at Table II, togetherwith the results of the burn tests.

TABLE II Expandable SBS SBS Sample Asphalt Graphite Colemanite I IITackifier Flow 5 65.49 4.00 19.50 3.38 3.25 4.39 Very slow flow, thickchar 6 75.19 2.60 11.01 3.15 2.56 5.50 little or no flow, thick char(initial heavy flow) 7 76.85 4.00 5.15 4.00 4.00 6.00 Little or no flow,thick char 8 66.00 4.00 20.00 4.00 4.00 2.00 Very slow flow, thick char9 67.94 4.00 15.56 2.50 4.00 6.00 Very slow flow, thick char 10 80.764.00 5.00 2.50 2.54 5.20 Very slow flow, thick char 11 64.37 3.13 20.004.00 2.50 6.00 Little or no flow, thick char 12 69.73 2.42 20.00 2.503.35 2.00 Slow flow, thick char 13 78.72 4.00 8.73 3.06 3.50 2.00 Slowflow, thick char 14 83.13 3.38 5.00 4.00 2.50 2.00 Very slow flow, thickchar 15 67.94 4.00 15.56 2.50 4.00 6.00 Slow flow, thick char 16 70.874.00 18.13 2.50 2.50 2.00 Very slow flow, thick char 17 64.37 3.13 20.004.00 2.50 6.00 Little or no flow, thick char 18 73.99 2.21 12.59 4.003.22 3.99 Slow flow, thick char 19 81.27 2.82 5.00 2.91 4.00 4.00 Slowflow, char 20 82.28 1.00 9.27 2.50 2.95 2.00 Heavy flow, drip 21 64.821.63 20.00 3.56 4.00 6.00 medium flow, char 22 82.00 1.00 5.00 4.00 2.505.50 Heavy flow, drip 23 69.07 1.00 20.00 2.50 2.50 4.93 Heavy flow,drip 24 75.65 1.00 13.46 2.50 4.00 3.39 Heavy flow, drip 25 84.36 1.005.00 3.73 3.91 2.00 Heavy flow, drip 26 71.90 1.00 15.98 2.63 2.50 6.00medium flow, dripped some 27 73.09 1.00 18.02 3.39 2.50 2.00 Heavy flow,drip 28 87.00 1.00 5.00 2.50 2.50 2.00 Heavy flow, drip 29 84.36 1.005.00 3.73 3.91 2.00 Heavy flow, drip 30 79.00 1.00 7.17 2.83 4.00 6.00Heavy flow, drip 31 82.00 1.00 5.00 4.00 2.50 5.50 Heavy, drip 32 82.201.00 5.00 2.50 3.30 6.00 Heavy flow, drip

As should be evident from the data presented in Table II, the additionof colemanite had negligible impact on the burn resistivity of themembranes. Instead, and quite unexpectedly, burn resistivity, ashighlighted by the flow of the material during the burn test, wasadvantageously impacted by the expandable graphite.

Samples 33-43

In an effort to compare the performance of expandable graphite in thepractice of the present invention with other intumescent materials, 11additional samples were prepared and tested. Specifically, eachformulation included 81 percent by weight asphalt, 7 percent by weightSBS copolymer I, 7 percent by weight limestone, and 5 percent by weightof the flame retardant identified in Table III. Table III also providesthe results of the burn test performed on each sample.

TABLE III Max Total Sample Ingredients Char Flow Dripping Temp Time TimeSelf Ext. No. Flame Retardant (Yes/No) (Yes/No) (Yes/No) (° F.) (s)(min) (Yes/No) 33 None N Y Y 950 42 1 Y 34 Expandable Graphite Y N N1150 240 4 Y 35 Ammonium N Y Y 1227 44 1 No Polyphosphate I 36 AmmoniumN Y Y 1131 60 1 Y Polyphosphate II 37 Ammonium N Y Y 1385 60 1 YPolyphosphate III 38 Ammonium N Y Y 1857 60 1 Y Polyphosphate IV 39Limestone N Y Y 1880 37 1 Y 40 Colemanite N Y Y 1990 38 1 Y 41 Al(OH)₃ NY Y 1858 27 1 Y 42 Mg(OH)₂ N Y Y 1365 60 1 No 43 Zinc Borate N Y Y 151260 1 No

The ammonium polyphosphate I was obtained under the tradename AP 760(Clariant); the ammonium polyphosphate II was obtained under thetradename CROS 486 (Budenheim); the ammonium polyphosphate III wasobtained under the tradename CROS 484 (Budenheim); the ammoniumpolyphosphate IV was obtained under the tradename CROS C30 (Budenheim);and the zinc borate was obtained under the tradename FireBrake ZB.

As should be appreciated from the data within Table III, the membraneprepared using expandable graphite was the only sample that couldwithstand the burn test. Indeed, the test was extended for the full fourminute length. All other samples had to be extinguished within oneminute for safety reasons.

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. A method for producing an asphaltic sheet, themethod comprising: (i) providing an asphaltic sheet; and (ii) applyingexpandable graphite particles to the asphaltic sheet.
 2. The method ofclaim 1, where said step of applying includes dropping the expandablegraphite onto a sheet that has been coated with molten asphalt, andwhere the expandable graphite is dropped at a rate and amount to createat least a partial layer of expandable graphite particles adjacent tothe asphalt of the coated asphalt sheet.
 3. The method of claim 1, wheresaid step of applying includes at least partially embedding some of thegraphite particles in to the asphalt such that the asphalt serves as abinder to hold the graphite particles in place or serves to adhere thegraphite particles to the surface of the sheet.
 4. The method of claim1, where said step of applying includes dropping expandable graphite onto an asphaltic sheet after the asphaltic sheet is prepared from amolten asphalt composition and prior to a substantial cooling of theasphalt material.
 5. The method of claim 1, where the expandablegraphite is in particulate form and is applied to the asphaltic sheet bydropping the expandable graphite particles in particulate form.
 6. Themethod of claim 1, where the asphaltic sheet is formed by saturating areinforcing textile with a molten asphaltic composition.
 7. The methodof claim 1, where the expandable graphite is characterized by an onsettemperature of at least 160° C.
 8. The method of claim 7, where theexpandable graphite is characterized by an onset temperature of at least180° C.
 9. The method of claim 1, further comprising the step oflaminating a polymeric sheet to the asphaltic sheet carrying theexpandable graphite.
 10. The method of claim 9, where the polymericsheet is mated to the asphaltic sheet at the planar surface carrying theexpandable graphite.
 11. The method of claim 10, further comprising thestep of removably mating a release film to the asphaltic sheet on theplanar surface opposite the surface to which the expandable graphite hasbeen applied.
 12. The method of claim 1, where said step of applyingexpandable graphite creates a concentration gradient of expandablegraphite where the concentration of the expandable graphite decreasesfrom a first surface to a lower region within the asphaltic sheet. 13.An asphaltic sheet comprising: (i) an asphaltic component including anasphalt binder; and (ii) a layer including expandable graphite, wheresaid layer is adjacent to said asphaltic component.
 14. A compositesheet comprising: (i) a planar body including asphalt material, saidplanar body having first and second opposed planar surfaces; (ii)expandable graphite deposited on said first planar surface.